Opposed free piston engine



April 10, 1956 R. HUBER OPPOSED FREE PISTON ENGINE 2 Sheets-Sheet 1 Filed Nov. 21 1950 April 10, 1956 R. HUBER QPPOSED FREE PISTON ENGINE 2 Sheets-Sheet 2 Filed Nov. 21 1950 q m, 5% Z M N w M m ./A m 03 United States Patent OPPOSED FREE Prs'roN ENGINE Kolierf Huber, Bellevne, France, assignor to Societe diEtudes et de Participatio'ris Ean, Gaz, Electricite, Ener re, S. A., Geneva, Switzerland, a society of Switzerla'nd Application November 21, 1950, Serial No. 196,767 Claims priority, application France November 33, 1949 Claims. (Cl. 123-46) The present invention relates to free piston machines and it is more particularly but not exclusively concerned machines having their pistons moving in opposed diretions. I

The term free piston machines designates machines incl-riding an internal combustion motor portion, preferably of the two-stroke type, and a compressor (or pump) portion, the motor and compressor (or pump) pistons being rigid with one another.

Among free piston machines, the present invention is mere especially concerned with motor compressors and anteenerators.- A motor compressor is a machine the compressor portion of which delivers directly at least a great portion of the air compressed in this compressor portion, whereas an auto-generator is a machine in which at least a portion of the air compressed in the compressor portion serves to supercharge the motor portion, which finally delivers a mixture of air under pressure and incompletely expanded combustion gases, this mixture servpreferably to operate a gas turbine.

The object or the present invention is to provide a machine of this kind which is better adapted to meet the requirements of practice than those existing at the present time; The chief feature of my invention relates to 'n'lacl'linesv having their opposed free pistons connected together by a synchronizing system constituted by two mechanisms dated on either side of the machine respectively and including each two crossed levers, each connected by means of links opposed pistons, one of these levers being substantially perpendicular to the direction of movement of said pistons when said pistons are at the ends of their outward strokes, whereas the other lever comes into this perpendicular position when the pistons are at the ends of their inward strokes. According to my invention, the first mentioned lever of one of these mechanisms is arranged to operate one or more auxiliary devices when the pistons are close to the ends of their outward strokes and the other leve'r of the same mechanism is arranged to oper ate one or more auxiliary devices when the pistons are close to the ends of their inward strokes.

Another feature of my invention consists in interposing a multiplying gear between an oscillating part, for instance an oscillating lever, of a synchronizing system and an auxiliary device, in particular a piston stroke limiting safety device, controlled by said oscillating part.

Still another feature of my invention consists in varying the output of the lubricating device of a free pistonmachine, for instance an auto-generator, in accordance with the length of stroke of the free piston or pistons.

A preferred embodiment of my invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

Fig. 1 diagrammatically shows one of the mechanisms of a synchronizing system for an opposed free piston machine;

Fig. 2 is a sectional view showing the same mechanism mounted in its casing and the means through which the 2 crossed levers of this mechanism control some auxiliary devices of the free piston machine;

Fig. 3 shows a modification of Fig. 1;

Fig. 4 shows, similarly to Fig. 2, the means through which the synchronizing mechanism according to Fig. 3 controls some auxiliary devices.

The opposed free piston machine, for instance a motor compressor or an auto-generator, may be of the" construction described in the U. S. Patent No. 2,442,470 to Raul Pate'ras Pes'cara'.

Each of the synchronizing mechanisms provided on either side of the motor cylinder includes two levers 1 and 2 of different lengths, which oscillate about a common axis XX (see Fig. 2). One end of each of these levers is connected with a rod 7 rigid with one of the opposed free pistons, to wit 3]; (through link 5 and hinge 6 for lever 1 and through link 4, link 5 and hinge 6 for lever 2). The other ends of these levers 1 and 2 are similarly connected, through links 4a and 5a and hinge 6a; with a rod7a rigid with the other piston 31a. The position indicated by the solid lines of Fig. 1 corresponds to the end of the outward strokes of the pistons, lever 1 being then substantially at right angles to the axis of the machine.

The position indicated in dotted lines on Fig. 1 for some of the elements of the mechanism corresponds to the end of the inward strokes of the pistons, Where lever 2 is in a direction substantially at right angles to the axis of the machine. The length of stroke between these two end positions is equal to the distance a between the two end positions A and B of hinge 6.

According to my invention, this mechanism, located on one side of the machine, is used to control both an auxiliary device connected with lever 1 so as to be operated when the pistons are close to the ends of their outward strokes and an auxiliary device connected with lever 2 so as to be operated when the pistons are close to the ends of their inward strokes.

According to an advantageous construction shown by Fig. 2, a shaft 3 is made rigid with one of the two above mentioned levers, for instance with lever 2, and this shaft extends through the side plate 8 of casing 9 which contains the mechanism in question. The end of shaft 3 which is located on the outside of casing 9 carries means, for instance a cam 10, for operating the injection pump 11 of the free piston machine, so as to cause injection to take place when the pistons are close to the ends of their inward strokes. V Furthermore, lever 1 is mounted rotatable on shaft 3. Preferably, lever 1 is constituted by two elements 1a and 112 located on either side of lever 2 and connected together at their ends by pins 16 which constitute the pivots through which lever 1 is hinged with links 5 and 5a. Lever 1 is made rigid with a sleeve 12 which surrounds shaft 3 and also extends through the side plate 8 of casing 9. The outer end of sleeve 12, between side plate 8 and cam 10, carries a cam 13 or the like which operates, through a push-piece 1 4 and a rod 15, an auxiliary device intended to Work when the pistons are close to the ends of their outward strokes.

According to the modification shown by Figs. 3 and 4, the shaft actuated by lever 1 is not coaxial with the shaft actuated by lever 2 but these two shafts are parallel to each other and disposed side by side. This is why lever 1 carries, rigid therewith, a toothed piece 16 in mesh with a pinion 17 mounted on the inner end of a shaft 18 which extends through the side plate 8 of casing 9 and which is parallel to shaft 3 and at a distance therefrom.

The arrangement of shafts 3 and 18 side by side makes it possible to fix on each of them an indicator (disc, needle, etc.) "'19, 20, one of these indicators indicating the end of the inward strokes and the other the end of the outward strokes of the pistons.

, In the embodiment shown by Fig. 4, the device actuatedby cam 21 mounted on shaft 18 is a safety device which stops the operation of injection pump 11' when the pistons are moving'outwardly beyond the limit admissible for normal operation of the machine. For this purpose, cam 21 opens, as soon as the pistons move-beyond this limit, a valve :22 interposed in the circuit 23 of a fluid (for instance air) under pressure which leads tothe lower chamber of a cylinder 24 containing a piston 25 rigid with the push-piece 26 actuated by cam to drive the piston of pump 11. Opening of valve 22 causes piston to be lifted, which stops the working of pump 11.

The fact of using, according to my invention, the two crossed levers 1 and 2 of the same synchronizing mechanismvlocated on one side of the free piston machine,

has the a'dvantage,among others, of a great simplification in construction and it makes it possible to use substantially identical link systems (with the difference of toothed sector 16 and the lengths of shafts 3 and 12).

'It also makes it possible to observe on the same side of the machine the inward and outward stroke end indicators 19, 20.

According to another feature of my invention, pinion 17, whichris in mesh with toothed sector 16, is made of a diameter smaller than that of said sector so as thus to obtain a multiplication in the transmission from lever 1 to shaft 18. r

This amplifies the angular movements of shaft 18 and'improves' the precision and sensitivity with which the auxiliary device or devices actuated by this shaft are operated.

According to still another feature of my invention,

' the auxiliary device operated by lever 1 (for instance 1 up to the present time, could not be avoided and which, 'driven by the motor gases, clogged the turbine supplied with these gases.

Still another feature of my invention relates to the way in which the two elements In and 1b of lever 1 are connected together. 7 7

According to my invention, these connecting means, which project slightly from the outer surface of at least one of the elements 1a and 1b, are disposed not at the ends of these elements but at places located between these ends and the axis of rotation of the lever, whereby these connecting means are constantly located on the outside of the slideways 9a which serve to guide shoes (not shown) as are usually mounted on pivots 6 and 6a through which links 5 and 5a are hinged to rods 7 and 7a.

Thus, in the embodiments shown by Figs. 2 and 4, elements 1a and 1b are connected together bytmeans of bolts 27 located approximately midway between the axis of shaft 3 and pivot pin 10 and screwed at one of their ends 27a in one of the elements, for instance element In, whereas the other threaded end passes through an orifice 28 providedrin the other element 1b and carries a nut 29 on the, outer side of this element 1b. A

' sleeve 30 surrounding each bolt 27 keeps elements 1a and 1b at the desired distance from each other.

projects externally from element 1b is located, for all positions of lever 1, outside guideway 9a. Consequently,

4 r r a this nut never has to pass through the aperture 9b of this guideway, the width of which can therefore be made equal, with the provision of a small play, to the distance between the outer surfaces of elements 1a and 1b. I thus avoid a reduction of the bearing surfaces of guideways 9a, which reduction would be unavoidable if slots 9b had to be made of greater width to afford passage for the connecting means projecting from at least one of the outer surfaces of elements 1a and 1b. a

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eflicient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

l. in combination with a machine including a frame and at least two opposed free pistons, means for synchronizing the movements of said pistons including, on the same side of said machine, two crossed levers pivoted to said frame about a common axis at right angles to the direction of movement of said pistons and links for connecting the opposed ends of each of said levers with said pistons respectively so that one lever is at least substantially perpendicular to said direction when said pistons are at the ends of their outward strokes and the. other lever is in turn at least substantially perpendicular to said direction when said pistons are at the ends of their inward strokes, at least one auxiliary device mounted on said frame, means operative by the first mentionedtlever for causing said auxiliary device to work when said pistons are close to the ends of their outward strokes, at least another auxiliary device mounted on said frame and means operative by the second mentioned lever for causing said second mentioned auxiliary device to work when said pistons are close to the ends of their inward strokes.

2. In combination with a machine including a frame and at least two opposed free pistons, means for synchronizing the movements of said pistons including, on the same side of said machine, two crossed levers pivoted to said frame about a common axis at right angles'to the direction of movement of said pistons and links for con necting the opposed ends of each of said levers with said pistons respectively so that one lever is at least substan- 'ing said auxiliary device to work when said pistons are close to the endsrof their outward strokes.

3. In combination with a machine including a frame and at least two opposed free pistons, means for synchronizing the movements of said pistons including, on the same side of said machine, two crossed levers pivoted to said frame about a common axis at right angles to thedirection of movement of said pistons and links for connecting the opposed ends of each of said levers with said pistons respectively so' that one lever is at leastsubstautially perpendicular to said direction when said pistons are at the ends of their inward strokes and the other lever is in turn at least substantially perpendicular to said direction when said pistons are at the ends of their outwardtstrokes,

a fuel injection device for said machine mounted on said,

frame, means operative by the first mentioned lever for causing said injection device to work when said pistons are close to the ends of their inward strokes, a cut-off device for stopping the operation of said fuel injection device and means operative by the second mentioned lever for causing said cut-ofi device to work when said pistons are moving beyond a given position in the outward direction.

4. A machine according to claim 1 further including a multiplying gear between one of said auxiliary devices and the lever by which it is operated.

5. A machine according to claim 1 in which one of said levers includes two parallel elongated plates located on either side of the other lever, and means, projecting from the outer face of at least one of said plates for securiug them together, such securing means being located midway between the common axis of said levers and each end of said lever.

References Cited in the file of this patent UNITED STATES PATENTS Pescara June 22, Pescara Oct. 31, Pescara June 3, Farmer Sept. 24, Muntz Sept. 24,

FOREIGN PATENTS France Sept. 26, Great Britain July 6, 

